NOt likely. If anything it could be from being knocked on a hard surface and its a type of bruise. If you sprained your ankle it would cause sweeling your ankle itself and proabably a fair amount of bruising.
Yes it is possible. If you have a severe strain in your ankle it is possible that the muscle was stretched as well as the ligaments causing a knot higher up in the leg. Apply ice to the entire area and elevate and it should go away.